Apparatus for accumulating and transporting stacks of paper sheets and the like

ABSTRACT

An apparatus for gathering successive sheets of a scalloped stream in an adjustable receptacle has a pivotable first stop in front of and a longitudinally adjustable second stop behind the receptacle. The second stop is shifted, together with the conveyor for the stream, toward or away from the first stop when the length of the sheets forming the stream is changed. The effective width of the receptacle is adjusted when a stream of relatively narrow sheets is followed by a stream of wider sheets or vice versa.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to improvements in apparatus foraccumulating successive sheets of short or long series of sheets intopiles or stacks of overlapping sheets at a stacking station, and forremoving stacks from a sheet-gathering receptacle at the stackingstation. More particularly, the invention relates to improvements inapparatus which can automatically remove successive freshly gatheredstacks while the sheets continuously arriving at the stacking stationgather into fresh or growing stacks of overlapping sheets. Apparatus ofsuch character are known as sheet piling devices, and one thereof isdescribed and shown in U.S. Pat. No. 4,436,472 granted Mar. 13, 1984 toKunzmann.

[0002] The patent to Kunzmann discloses an apparatus wherein severalstacking units are placed side-by-side. A drawback of the patentedapparatus is that its design imposes limits upon the number of stacks orpiles which can be gathered per unit of time with a requisite degree ofaccuracy. Moreover, the condition of the sheets is likely to be affectedif the rate at which the sheets are supplied and stacked exceeds arelatively low threshold value.

[0003] Another drawback of conventional apparatus of the above outlinedcharacter is that they cannot be rapidly converted for the stacking ofsheets having different sizes and/or shapes. This can result inprolonged interruptions of the operation and a considerable reduction ofthe output.

OBJECTS OF THE INVENTION

[0004] An object of the instant invention is to provide an apparatuswhich constitutes an improvement over and an advantageous furtherdevelopment of apparatus disclosed in the aforementioned U.S. Pat. No.4,436,472 to Kunzmann.

[0005] Another object of the invention is to provide an apparatus whichcan be rapidly converted to gather larger or smaller, wide or narrowerand/or shorter or longer sheets with the same degree of accuracy.

[0006] A further object of the present invention is to provide novel andimproved means for manipulating one or more abutments for the growingstacks of paper sheets or the like.

[0007] An additional object of the invention is to provide a novel andimproved method of manipulating successive sheets of a stream or flow ofpartially overlapping sheets in a stacking machine.

[0008] Still another object of the invention is to provide a sheetstacking apparatus which can gather sheets of different thicknessesand/or other characteristics with the same degree of accuracy andpredictability.

[0009] Another object of the invention is to provide a novel andimproved method of manipulating scalloped streams of partiallyoverlapping paper sheets or the like preparatory to and duringconversion or gathering into stacks or piles.

[0010] Still another object of the invention is to provide an apparatuswhich can be reliably converted for the processing of sheets havingdifferent sizes and/or shapes within short intervals of time.

SUMMARY OF THE INVENTION

[0011] The invention resides in the provision of an apparatus forgathering successive sheets of a series of sheets (such as paper sheets)into growing stacks which are being gathered in and, when fully grown,are removed from a receptacle at a stacking station. The apparatuscomprises means for conveying successive sheets of the series (e.g.,successive sheets of a scalloped stream consisting of partiallyoverlapping sheets) in a first direction (e.g., substantiallyhorizontally) into the receptacle at the stacking station to thusaccumulate in the receptacle a growing stack of overlying or overlappingsheets, front and rear abutments or stops for the sheets of a stack inthe receptacle (the abutments are spaced apart from each other in thefirst direction and the front abutment is movable relative to thereceptacle between operative and inoperative positions), means forwithdrawing fully grown stacks from the receptacle in the firstdirection while the front abutment dwells in the inoperative position,means for transporting withdrawn stacks in a second direction (e.g.,substantially horizontlly and substantially at right angles to the firstdirection), and means for adjusting the rear abutment in and counter tothe first direction. The conveying means can comprise a belt or chainconveyor or another suitable conveyor which can deliver to thereceptacle sheets having different lengths, and the rear abutment isadjustable for the purpose and to the extent necessary to conform thespacing of the front and rear abutments from each other to the lengthsof sheets being conveyed to the receptacle.

[0012] The apparatus can further comprise a platform which can resembleor constitute a rake and serves to separate the sheets. The platform ismovable with the conveying means between a plurality of positions, suchas forwardly and backwards (as seen in the first direction) and/or upand down. The movements of the platform in and counter to the firstdirection can take place in synchronism with movements of thewithdrawing means (the latter can include gripper or holder meansadapted to engage the front end portion of a fully grown stack and topull the stack from the receptacle while the front abutment ismaintained in its inoperative position).

[0013] The conveying means is or can be arranged to share the movementsof the platform between a plurality of different levels.

[0014] In accordance with a presently preferred embodiment, theapparatus further comprises a carriage (such as a slide) for theaforementioned platform and for the conveying means, as well as anelevator which serves to move the carriage between a plurality ofdifferent levels. The carriage is movable (preferably relative to theelevator) in and counter to the first direction, and the elevator ismovable up and down relative to the receptacle at the stacking station.

[0015] The mounting of the platform on the carriage is or can be suchthat the platform is movable relative to the carriage in and counter tothe first direction through distances corresponding to the extent ofadjustment of the rear abutment relative to the front abutment.

[0016] The forward end of the sheet conveying means is preferablydisposed at a predetermined (fixed) distance from the platform.

[0017] The receptacle can be provided with an exchangeable bottom wall,and such bottom wall can include an exchangeable substantiallystrip-shaped holder as well as a plurality of sheet supporting rakescarried by the holder. The holder can further carry lateral stops andguide means for the lateral stops.

[0018] The novel features which are considered as characteristic of theinvention are set forth in particular in the appended claims. Theimproved apparatus itself, however, both as to its construction and itsmode of operation, together with numerous additional important andadvantageous features and attributes thereof, will be best understoodupon perusal of the following detailed description of certain presentlypreferred specific embodiments with reference to the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019]FIG. 1 is a schematic elevational view of an apparatus whichembodies one form of the invention, a fully grown stack of overlappingsheets being about to be transferred from the stacking station onto anevacuating conveyor;

[0020]FIG. 1a shows the apparatus of FIG. 1 but in the process ofgathering a next-following stack of sheets at the stacking station;

[0021]FIG. 1c shows the structure of FIG. 1 during a further stage ofgathering the next-following stack at the stacking station and with thestack withdrawing unit retracted from the position of FIG. 1b back tothe front stop at the stacking station;

[0022]FIG. 1d shows the structure of FIG. 1c but with the rear stop in araised position;

[0023]FIG. 2a shows the apparatus of FIG. 1a but in the course ofgathering a stack of sheets shorter than those shown in FIGS. 1a to 1 d;

[0024]FIG. 2b shows the apparatus of FIG. 2a but during gathering of anext following stack of shorter sheets;

[0025]FIG. 3 is an enlarged fragmentary partly sectional view of adetail in the apparatus of FIGS. 1a to 1 d; and

[0026]FIG. 4 is a plan view of the detail shown in FIG. 3.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0027] The apparatus which is shown in FIG. 1a comprises a stackcollecting receptacle 4 which is located at a stacking station 1 andreceives successive sheets 2 of a scalloped stream of (partiallyoverlapping) sheets to gather a series of successive stacks 3 ofoverlapping sheets. As a rule, or at least in many instances, theimproved apparatus comprises a battery of two or more receptacles 4 eachof which receives successive sheets of a discrete scalloped stream ofsheets 2, i.e., each of which gathers a discrete series of stacks 3. Thereceptacles 4 are located one behind the other, as viewed in FIG. 1a.

[0028] The sheets 2 of the stream shown in FIG. 1a are conveyed by abelt or band conveyor 7 which is operated to advance the partiallyoverlapping sheets in the direction of the arrow 6. The receptacle 4 ofFIG. 1a is followed by a stack withdrawing or removing unit 8 includinggrippers or tongs 5, and the tongs 5 are followed by an evacuatingconveyor 9. The latter is designed to transport the (withdrawn) stacks 3sideways, i.e., at right angles to the plane of FIG. 1a. In thisembodiment, the conveyor 9 comprises stack-advancing endless belts 11with integrated pneumatic table segments 12.

[0029] The sheets 2 of the growing stack 3 in the receptacle 4 arebounded by a front or downstream abutment or stop 13 and a rear orupstream abutment or stop 14 (as seen in the direction of the arrow 6).The front abutment is pivotable between an operative position (see FIG.1b), in which it is located in front of and at a level above the growingstack of sheets 2 in the receptacle 4, and an inoperative or retractedposition (FIG. 1a) at a level beneath the bottom part of the receptacle.

[0030] The rear abutment or stop 14 can comprise several sections (thesame holds true for the abutment 13) and is mounted on a slide orcarriage 16 which is movable in directions indicated by a double-headedarrow 15. The carriage 16 further supports the conveyor 7 as well as arake-like platform 17 which serves as a separator and is movable withand also relative to the carriage 16. The platform 17 can perform(relative to the carriage 16) strokes of variable length.

[0031] The discharge or downstream end 18 of the conveyor 7 is locatedat a fixed distance from the platform 17. The carriage 16 is mounted onand is movable relative to a support 21 which can be said to constitutean elevator because it is movable up and down in directions indicated bya double-headed arrow 19.

[0032] The receptacle 4 comprises a bottom wall or panel 22 whichincludes a plurality of parallel supporting rakes 23 secured to astrip-shaped holder 24 (see FIGS. 3 and 4). The holder 24 is providedwith transversely extending guides 26 for lateral stops 27 which can befixed in selected guides 26, in dependency upon the format (size) of thesheets 2 and stacks 3, by distancing members.

[0033] Several bottom panels 22 can be assembled with suitable lateralstops 27 into preassembled groups or modules which are held in positionsof readiness for eventual use in a manner and for purposes as will bedescribed hereinafter.

[0034] The mode of operation is as follows:

[0035]FIG. 1a shows a fully assembled pile or stack 3 consisting of apredetermined number of sheets 2 being confined in the receptacle 4. Thefront abutment 13 (or the illustrated one of two or more frontabutments) is already pivoted to its inoperative position, and thegripper or tongs 5 of the illustrated withdrawing unit 8 is ready toadvance the freshly assembled stack 3 in the direction of the arrow 6,namely onto the evacuating conveyor 9. The latter is designed to advancethe thus received stack 3 in a direction toward or away from theobserver of FIG. 1b.

[0036] The illustrated gripper 5 of the withdrawing unit 8 operates insynchronism with the platform 17 which comprises the aforementionedsupporting rake and shares the forward movement of the fully assembledstack 3 in the direction of the arrow 6. FIG. 1b shows a fully assembledstack 3 on the conveyor 9 and the next-following (growing) stack 3 inthe process of growing on top of the platform 17. Thus, the delivery ofsheets 2 by the conveyor 7 need not be interrupted while the trailingabutment 14 establishes a path for advancement of successive sheets 2 ofthe scalloped stream of sheets toward and against the front abutment 13which (see FIGS. 1b and 1 c) is again in the operative position in whichit intercepts the oncoming sheets 2.

[0037] The support or elevator 21 descends, as indicated by the lowerhalf of the arrow 19 (FIG. 1c), to lower the platform 17 so that itreaches or descends even below the level of the panel 22, and isthereupon retracted to the position shown in FIG. 1d. Such manipulationof the elevator 21 results in the deposition of the growing stack 3 ofsheets 2 on the panel 22 of the receptacle 4.

[0038] The next step involves an upward movement of the elevator 21 (asindicated by the upper half of the arrow 19); this entails a lifting ofthe discharge end 18 of the conveyor 7 to a level such that it rises atthe rate at which the height of the growing stack 3 on the platform 22increases. Such mode of operation is desirable and advantageous becauseeach sheet 2 of successively delivered sheets supplied by the conveyor 7descends through the same distance. This contributes to uniformity ofthe successively accumulated stacks 3.

[0039]FIGS. 2a and 2 b illustrate the manner in which the improvedapparatus can be adjusted to permit for the accumulation of stacks ofsheets smaller or larger than the sheets 2 shown in FIGS. 1a to 1 d. Thecarriage 16 is moved in one of the directions indicated by thedouble-headed arrow 15, and this results in identical movements of therear abutment 14 as well as of the discharge end 18 of the conveyor 7and of the platform 17. Thus, the distance between the abutments 13 and14 is reduced accordingly (it is assumed here that the carriage 16 hasbeen moved in a direction to the right, as viewed in FIG. 1a).

[0040] If one desires to change the effective width of the receptacle 4,i.e., to stack narrower or wider sheets, it is merely necessary toreplace the aforementioned module 22, 27 with a different module.

[0041] The extent of movement of the platform 17 in or counter to thedirection indicated by the arrow 6 is changed as a function of change ofthe distance between the front and rear abutments 13 and 14. The lengthof the forward stroke of the gripper 5 remains unchanged due to theabsence of any appreciable changes of the forward stroke of the stackremoving unit 8. In fact, the length of the forward stroke is reduced ifthe format (size) of the sheets 2 is reduced.

[0042] An important advantage of the improved apparatus is that the justdiscussed changes of the format of the stacks 3 can be carried out in asimple and timesaving manner. This is accomplished by the provision (a)of the carriage 16 which supports the platform 17 and the rear orupstream abutment 14, and (b) of the means for moving the carriage 16 upand down (arrow 19) as well as forwardly and backwards (arrow 15).Furthermore, the carriage 16 supports the conveyor 7 at a fixed distancefrom and above the platform 17.

[0043] Another advantage of the improved apparatus is that theaforedescribed changes of the format can be carried out withoutnecessitating any changes in the position and/or movements of the frontor downstream abutment(s) 13. This, in turn, ensures that the stroke orstrokes of the gripper or grippers 5 can remain unchanged.

[0044] A further important advantage of the improved apparatus is thatthe discharge end 18 of the sheet supplying conveyor 7 and the platform17 share the movements in directions indicated by the double-headedarrow 19; this ensures that the extent of descent of successive sheets 2from the conveyor 7 into the receptacle 4 is the same while a stack 3 isin the process of growing in the receptacle as well as during withdrawalof a fully grown stack from the receptacle (while the conveyor continuesto deliver sheets toward and beyond the discharge end 18).

[0045] An additional important advantage of the improved apparatus isthat the carriage 16 (which is movable in directions indicated by thedouble-headed arrow 15) carries the conveyor 7, the rear abutment 14 andthe platform 17. This renders it possible to complete any requiredadjustments within a surprisingly short interval of time, i.e., theparts 7, 16 and 17 can be adjusted as a unit.

[0046] Additional savings in time and space are achieved by theprovision of the elevator 21 which is movable up and down (arrow 19) andsupports the carriage 16 in such a way that the latter is movable indirections indicated by the arrow 15. Such practically universalmovability of the carriage 16 with and relative to the elevator 21contributes to simplicity and predictability of stacking of sheets inthe receptacle 4 as well as to rapid conversion of the apparatus for thestacking of larger, smaller, narrower or wider sheets. The movements ofthe platform 17 in dependency on the selected format of stacks 3 can besimplified and rendered more precise by selecting the extent ofmovements of the platform in directions indicated by the arrow 15 toconform to the selected distance between the front and rear abutments 13and 14.

[0047] The features which are illustrated in and which were describedwith reference to FIGS. 3 and 4 contribute to a simplification ofadjustments which are to be carried out when the conveyor 7 is todeliver narrower sheets 2 following the delivery of a series of widersheets or vice versa.

[0048] An advantage of the feature that the mounting of the frontabutment 13 can remain unchanged when the length of the sheets 2 ischanged from shorter to longer or vice versa is that the strokes whichare being performed by the grippers 5 can remain unchanged. Thissimplifies the design of the stack withdrawing unit 8 as well as of theevacuating conveyor 9.

[0049] To summarize: The improved apparatus renders it possible tosimplify the conversion from the stacking of sheets having a firstformat to the stacking of sheets having a different second format and toenable the persons in charge to complete the conversion within asurprisingly short interval of time. Furthermore, the components whichrender such conversion possible are simple, compact and inexpensive.

[0050] Without further analysis, the foregoing will so fully reveal thegist of the present invention that others can, by applying currentknowledge, readily adapt it for various applications without omittingfeatures that, from the standpoint of prior art, fairly constituteessential characteristics of the generic and specific aspects of theabove outlined contribution to the art of apparatus for accumulating andtransporting stacks of paper sheets and the like and, therefore, suchaaptations should and are intended to be comprehended within the meaningand range of equivalence of the appended claims.

What is claimed is:
 1. Apparatus for gathering successive sheets of aseries of sheets into growing stacks in and for removing fully grownstacks from a receptacle at a stacking station, comprising: means forconveying successive sheets of the series of sheets in a first directioninto the receptacle to thus accumulate in the receptacle a growing stackof overlying sheets; front and rear abutments for the sheets of a stackin said receptacle, said abutments being spaced apart from each other insaid first direction and said front abutment being movable relative tosaid receptacle between operative and inoperative positions; means forwithdrawing fully grown stacks from the receptacle in said direction inthe inoperative condition of said front abutment; means for transportingwithdrawn stacks in a second direction; and means for adjusting saidrear abutment in and counter to said first direction.
 2. The apparatusof claim 1, wherein said means for conveying is arranged to deliver tosaid receptacle sheets having different lengths and said rear abutmentis adjustable to conform the spacing of said abutments from each otherto the lengths of sheets being conveyed to said receptacle.
 3. Theapparatus of claim 1, further comprising a platform adjacent to andmovable with said means for conveying between a plurality of differentpositions.
 4. The apparatus of claim 3, wherein said platform is movablerelative to said stacking station in and counter to said first directionin synchronism with said means for withdrawing.
 5. The apparatus ofclaim 3, wherein said means for conveying is arranged to share themovements of said platform between a plurality of different levels. 6.The apparatus of claim 3, further comprising a carriage for saidplatform and for said means for conveying, and an elevator for movingsaid carriage between a plurality of different levels.
 7. The apparatusof claim 6, wherein said carriage is movable in and counter to saidfirst direction.
 8. The apparatus of claim 6, wherein said carriage ismovable in and counter to said first direction relative to saidelevator.
 9. The apparatus of claim 8, wherein said elevator is movableup and down relative to said receptacle.
 10. The apparatus of claim 6,wherein said platform is movable relative to said carriage in andcounter to said first direction through distances corresponding to theextent of adjustment of said rear abutment relative to said frontabutment.
 11. The apparatus of claim 3, wherein said means for conveyinghas a forward end disposed at a predetermined distance from saidplatform.
 12. The apparatus of claim 1, wherein said receptaclecomprises an exchangeable bottom wall.
 13. The apparatus of claim 12,wherein said bottom wall includes an exchangeable substantiallystrip-shaped holder and a plurality of supporting rakes carried by saidholder.
 14. The apparatus of claim 13, further comprising lateral stopsand guide means for said stops provided on said holder.